U.S. patent number 5,286,260 [Application Number 07/891,419] was granted by the patent office on 1994-02-15 for modular hip prosthesis.
This patent grant is currently assigned to DePuy Inc.. Invention is credited to Richard Bolesky, Todd S. Smith, Charles E. Whitcraft, Jr..
United States Patent |
5,286,260 |
Bolesky , et al. |
February 15, 1994 |
Modular hip prosthesis
Abstract
A modular hip prosthesis for the replacement of a portion of the
femur is provided. The prosthesis is assembled from a kit that
includes a stem member having an upper portion and a lower portion,
with the lower portion sized to be received in the femur. The kit
also includes a body member that is sized to replace a portion of
the femur and is configured to be received over the upper portion
of a stem member. The kit also includes a head member that is sized
to replace the head of the femur. A neck member is provided to
attach the head member to the body member to form an assembled
prosthesis.
Inventors: |
Bolesky; Richard (Warsaw,
IN), Smith; Todd S. (Warsaw, IN), Whitcraft, Jr.; Charles
E. (Warsaw, IN) |
Assignee: |
DePuy Inc. (Warsaw,
IN)
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Family
ID: |
25406966 |
Appl.
No.: |
07/891,419 |
Filed: |
May 29, 1992 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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450058 |
Dec 13, 1989 |
5181928 |
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896857 |
Aug 15, 1986 |
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Current U.S.
Class: |
623/22.42 |
Current CPC
Class: |
A61F
2/36 (20130101); A61F 2002/30433 (20130101); A61F
2002/30387 (20130101); A61F 2002/30354 (20130101); A61B
2090/031 (20160201); A61F 2230/0069 (20130101); A61F
2/30728 (20130101); A61F 2002/30507 (20130101); A61F
2002/3686 (20130101); A61F 2002/30113 (20130101); A61F
2310/00395 (20130101); A61F 2/367 (20130101); A61F
2002/30906 (20130101); A61F 2002/365 (20130101); A61F
2002/3625 (20130101); A61F 2220/0025 (20130101); A61F
2220/0033 (20130101); A61F 2/30767 (20130101); A61F
2002/30481 (20130101); A61F 2002/30331 (20130101); A61B
2090/037 (20160201); A61F 2002/30373 (20130101); A61F
2002/3079 (20130101); A61F 2220/0041 (20130101); A61F
2002/30224 (20130101); A61F 2002/30616 (20130101); A61F
2/4607 (20130101); A61F 2002/30604 (20130101); A61F
2/3672 (20130101); A61F 2002/30729 (20130101); A61F
2/3676 (20130101); A61F 2002/30367 (20130101); A61F
2002/3674 (20130101); A61F 2002/30495 (20130101); A61F
2002/30405 (20130101); A61F 2230/0006 (20130101); A61F
2002/3652 (20130101); A61F 2/3609 (20130101); A61F
2/30907 (20130101) |
Current International
Class: |
A61F
2/36 (20060101); A61B 19/00 (20060101); A61F
2/00 (20060101); A61F 2/30 (20060101); A61F
2/46 (20060101); A61F 002/36 (); A61F 002/32 () |
Field of
Search: |
;623/16,18,19,20,23 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0163121A1 |
|
Apr 1985 |
|
EP |
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0198163A2 |
|
Feb 1986 |
|
EP |
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0190981A1 |
|
Aug 1986 |
|
EP |
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2318396 |
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Oct 1974 |
|
DE |
|
3406358 |
|
Dec 1984 |
|
DE |
|
3336005 |
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Apr 1985 |
|
DE |
|
1183230 |
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Dec 1973 |
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FR |
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2225141 |
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Aug 1974 |
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FR |
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2378505 |
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Jul 1976 |
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FR |
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2575383A |
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Dec 1984 |
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FR |
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2576793 |
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Jan 1985 |
|
FR |
|
1531487 |
|
Nov 1974 |
|
GB |
|
1443470 |
|
Jul 1976 |
|
GB |
|
1521679 |
|
Aug 1978 |
|
GB |
|
2070939 |
|
Sep 1981 |
|
GB |
|
WO83/02555 |
|
Aug 1983 |
|
WO |
|
Other References
Tumorprotheses des Huftgelenkes (Indikation und Ergebnisse); By: M.
Jager, L. Loffler, D. Kohn. .
Concept and Material Properties of a Cementless hip Prosthesis
System with Al.sub.2 O.sub.3 Ceramic Ball Heads and Wrought
Ti-6Al-4V Stems; By: K. Zweymuller and M. Semlitsch..
|
Primary Examiner: Isabella; David
Attorney, Agent or Firm: Barnes & Thornburg
Parent Case Text
This is a division of application Ser. No. 07/450,058 filed Dec.
13, 1989, now U.S. Pat. No. 5,181,928 which is a continuation of
application Ser. No. 06/896,857 filed Aug. 15, 1986 (now
abandoned).
Claims
What is claimed is:
1. A modular hip prosthesis assembly for the replacement of a
portion of a femur, the assembly comprising
a stem member of a predetermined size and shape having an upper
portion and a lower portion and selected from a group consisting of
differently sized and shaped stem members, each of said stem
members lower portions sized and shaped to be received into said
femur,
a body member of a predetermined size and shape to replace a
portion of the femur and selected from a group consisting of
differently sized and shaped body members, each of said body
members configured to be received over one of said upper portions
of said stem members,
a head member of a predetermined size and shape to replace the head
of the femur and selected from a group consisting of differently
sized and shaped head members, and
a neck member of a predetermined size and shape selected from a
group consisting of differently sized and shaped neck members
demountably engageable with any one of said body members and
adapted to receive one of said head members in a spaced apart
relation from one of said body members.
2. The assembly of claim 1, further comprising a collar member of a
predetermined size and shape selected from a group consisting of
differently sized and shaped collar members and adapted to be
interposed between one of said body members and one of said neck
members.
3. The assembly of claim ,1 wherein said one neck member includes a
first end for engaging said one of said head members and a second
end for engaging said one of said body members, and wherein said
first end is formed to include a tapered projection that is sized
to be received into a tapered hole in said one of said head members
to secure said one of said head members to said one of said neck
members.
4. The assembly of claim 3, wherein said second end is formed to
include a tapered projection that is sized to be received into a
tapered hole in said one of said body members to secure said one of
said neck members to said one of said body members.
5. A kit for the assembly of a hip prosthesis for the replacement
of a head, neck, and adjacent portions of a femur, the neck of the
femur having a base defining a neck basal plane, the kit
comprising
at least one stem member having a predetermined shape and size to
be inserted into the shaft of the femur, said stem member selected
from a group consisting of differently sized and shaped stem
members, said group of stem members having generally uniformly
sized upper portions,
at least one body member adapted to mate with said stem member and
having a predetermined shape and size to replace a portion of the
femur and to define a plane generally coincident with said neck
basal plane, said body member selected from a group consisting of
differently sized and shaped body members, each body member in said
group of body members formed to include a generally uniformly sized
bore adapted to receive said upper portion of one of said stem
members
at least one neck member adapted to mate with said body member and
having a predetermined shape and size, said neck member selected
from a group consisting of differently sized and shaped neck
members, and
at least one head member adapted to mate with said neck member and
having a predetermined shape and size to replace the head portion
of the femur, said head member selected from a group consisting of
differently sized and shaped head members.
6. A modular hip prosthesis assembly for the replacement of a
portion of a femur, the assembly comprising
a stem member of a predetermined size and shape having an upper
portion and a lower portion and selected form a group consisting of
differently sized and shaped stem members, each of said stem
members lower portions sized and shaped to be received into said
femur,
a body member of a predetermined size and shape to replace a
portion of the femur and selected from a group consisting of
differently sized and shaped body members, each of said body
members configured to be attached to one of said upper portions of
said stem members,
a head member of a predetermined size and shape to replace the head
of the femur and selected from a group consisting of differently
sized and shaped head members, and
a neck member of a predetermined size and shape selected from a
group consisting of differently sized and shaped neck members
demountably engageable with any one of said body members and
configured to be attached to one of said head members in a spaced
apart relation from one of said body members.
7. The assembly of claim 6, further comprising a collar member of a
predetermined size and shape selected form a group consisting of
differently sized and shaped collar members and configured to be
interposed between one of said body members and one of said neck
members.
8. The assembly of claim 6, wherein said one neck member includes a
first end for engaging said one of said head members and a second
end for engaging said one of said body members, and wherein one of
said first ends of said neck member and said one head member is
formed to include a tapered portion that is located thereon and is
sized to be received into a tapered hole located in the other of
said one end of said neck member and said one head member,
respectively, to secure said one of said head members to said one
of said neck members.
9. The assembly of claim 8, wherein one of said second end and said
body members, respectively, is formed to include a tapered
projection that is sized to be received into a tapered hole in the
other one of said second end and one of said body members to secure
said one of said neck members to said one of said body members.
10. A kit for the assembly of a hip prosthesis for the replacement
of a head, neck, and adjacent portions of a femur, the neck of the
femur having a base defining a neck basal plane, the kit
comprising
at least one stem member having a predetermined shape and size to
be inserted into the shaft of the femur, said stem member selected
from a group consisting of differently sized and shaped stem
members, said group of stem members having generally uniformly
sized upper portions,
at least one body member adapted to mate with said stem member and
having a predetermined shape and size to replace a portion of the
femur and to define a plane generally coincident with said neck
basal plane, said body member selected from a group consisting of
differently sized and shaped body members, each body member in said
group of body members formed to include an attachment portion for
securement with said upper portion of one of said stem member,
at least one neck member adapted to mate with said body member and
having a predetermined shape and size, said neck number selected
form a group consisting of differently sized and shaped neck
members, and
at least one head member adapted to mate with said neck member and
having a predetermined shape and size to replace the head portion
of the femur, said head member selected from a group consisting of
differently sized and shaped head members.
Description
BACKGROUND AND SUMMARY OF THE INVENTION
The present invention relates to prostheses for replacement of a
portion of the hip joint. More particularly, the present invention
relates to a modular prosthesis for replacement of the upper
portion of the femur.
Conventional prostheses for the replacement of the upper portion of
the femur are generally unitary structures. The conventional
prosthesis generally includes a stem portion that is designed to
extend downwardly into a cavity within the femur. The stem portion
may be secured within the femur by the use of bone cement, or in
other adaptations, the stem may be configured to promote bone
ingrowth to secure the stem. The conventional hip prosthesis also
includes a neck portion that is integral with the stem portion. The
neck portion is configured to replace the neck of the femur which
will normally be resected with the head of the femur. Integrally
fixed to the neck portion will normally be a generally spherical
head portion that is configured to replace the head of the femur. A
collar may be provided between the neck portion and the stem
portion to stabilize the prosthesis on the resected femur.
Generally, the collar will rest upon the resected surface of the
femur to disperse the load on the prosthesis over a greater area,
and to compress the underlying bone. A collar may be provided
between the neck portion and the stem portion to stabilize the
prosthesis and function as a stop or reference point on the
resected femur.
Because conventional prostheses are generally unitary devices, the
practice has been to maintain a large inventory of prostheses of
different sizes to accommodate the different bone sizes that are to
be replaced. Generally, the patient is evaluated by x-ray or some
other means to determine the approximate bone size, and
consequently the approximate required prosthesis size. During the
replacement operation, several different prostheses are made
available as suggested by the evaluation. The appropriate
prosthesis is then selected for insertion into the patient at the
time of operation.
One problem with the conventional, unitary prosthesis is that the
hospital has to maintain a large number of differently sized
prostheses to accommodate different sizes of bones to be replaced.
Generally, a supply of prostheses with and without a collar also
must be maintained in the inventory. Also, prostheses with
different shapes and angles of the stem and neck portion must be
maintained. Even with this large inventory of prostheses, it is
often difficult to find a prosthesis that is sized and shaped
exactly for the individual patient.
Prostheses having a stem portion and a separate head portion are
known. One such prosthesis is shown in U.S. Pat. No. 4,051,559.
U.S. Pat. No. 4,051,559 discloses a prosthesis that includes a
separate threaded stem portion that is adapted to be screwed into a
prepared cavity within the femur. The prosthesis separately
comprises a head portion that includes a neck and collar that is
adapted to be mated with the stem portion. This prosthesis is not
designed to be assembled prior to insertion within the patient. The
stem portion must first be screwed into the cavity within the
femur. The head portion is then attached to the installed stem
portion by a bolt. The collar is designed to rest upon the resected
surface of the femur to support the load placed on the prosthesis.
Because of the design of the stem portion, the head portion must
include the collar in order to support the weight that will be
placed on the prosthesis. This prosthesis is limited in flexibility
because the stem portion must be straight in order to be screwed
into the femur. Also, the head portion, including the neck and
collar is a unitary structure which further reduces the flexibility
of the device.
Another prosthesis having a stem portion and a separate head
portion is shown in U.S. Pat. No. 3,806,957. U.S. Pat. No.
3,806,957 discloses a prosthesis that includes a separate stem
portion having a proximal end that is broadened somewhat. The
broadened proximal end of the stem is configured to receive a head
and threaded neck portion to form a complete prosthesis. The patent
discloses that the neck may be elongated or shortened depending on
the specific anatomy of different patients. This prosthesis, like
the prosthesis disclosed in U.S. Pat. No. 4,051,559, is limited in
flexibility because the head and neck portion is a unitary
structure, and because the head and neck portion attaches directly
into the stem portion.
A prosthesis in which the stem portion comprises more than one
component is shown in U.S. Pat. No. 3,987,499. U.S. Pat. No.
3,987,499 discloses a prosthesis having a stem or shank component
that includes two parts, an anchoring part and a transition part. A
ball is connected to the transition part. Also, a collar may be
included between the ball and a portion of the femur. The anchoring
part is provided with external threads that are adapted to tap
themselves into the femur. The transition part is coupled to the
anchoring part by a guide pin and securing screw. The ball is
adapted to be screwed onto the free end of the transition part. One
problem with the prosthesis disclosed in U.S. Pat. No. 3,987,499 is
that the prosthesis is designed to be placed in position within the
body component by component, and assembled sequentially. Another
problem with this prosthesis is that the neck is a part of the
transition part, which reduces the flexibility of the device. In
addition, the collar is configured to be supported only between the
bone and the ball, and is thus subject to rotational and toggling
instability.
One object of the present invention is to provide a modular hip
prosthesis that has a great deal of flexibility in its assembly,
both as to the size and shape of the assembled device.
Another object of the present invention is to provide a modular hip
prosthesis that may be assembled in the operating room before any
component is inserted into the patient.
Yet another object of the present invention is to provide a modular
hip prosthesis that is configured to function with or without a
collar.
Yet another object of the present invention is to provide a modular
hip prosthesis that includes a stem portion that may be shaped to
fit a curvature within the bone structure, if necessary.
According to the present invention, a kit for the assembly of a hip
prosthesis for the replacement of a portion of a femur is provided.
The kit comprises a stem member having an upper portion and a lower
portion, with the lower portion sized to be received into the
femur. The kit also comprises a body member that is sized to
replace a portion of the femur and is configured to be received
over the upper portion of the stem member. The kit also comprises a
head member that is sized to replace the head of the femur,
including means to attach the head member to the body member.
One feature of the present invention is that the kit preferably
consists of stem members, body members, and head members, and
attaching means all of various sizes and shapes. These separate
components are adapted to be assembled together to form a custom
prosthesis of a desired size and shape. One advantage of this
feature is that a hip prosthesis of a desired size and shape may be
assembled from the kit at the time of the operation.
Another feature of the present invention is that the kit comprises
body members that are inserted over the stem members and are
configured to bear a portion of the load that is exerted on the
prosthesis. One advantage of this feature is that the prosthesis
may be assembled without a collar component if the indications
presented during the operation suggest that a collar may not be
needed, or may produce unsatisfactory side effects.
In preferred embodiments of the present invention, the stem member,
body member, and the head member are selected from a group
consisting of differently sized and shaped members, respectively.
One feature of the foregoing structure is that with different sizes
and shapes of stem members, body members, and head members, the
number of combinations available to assemble a hip prosthesis is
greatly increased, without increasing the number of inventoried
components. One advantage of this feature is that the flexibility
of assembling a hip prosthesis for an individual patient is greatly
increased.
Also in preferred embodiments of the present invention, the
attaching means involves a neck member that is adapted to be
rigidly attached to the body member and to the head member. The
neck member is configured to replace the natural neck of the femur.
The neck member, like the stem member, body member, and head
member, is selected from a group consisting of differently sized
neck members to increase the flexibility of the prosthesis.
The modular hip prosthesis of the present invention thus provides
the ability to assemble a custom prosthesis by selecting different
sizes and shapes of individual components to meet the requirements
of the individual patient exactly. The provision of the kit concept
for the prosthesis greatly reduces the inventory required to be
maintained by the hospital. Also, the kit form of the prosthesis
increases greatly the flexibility of the system, and provides for
the assembly of a prosthesis that may otherwise be unavailable.
Additional objects, features, and advantages of the invention will
be apparent to those skilled in the art upon consideration of the
following detailed description of preferred embodiments
exemplifying the best mode of carrying out the invention as
presently perceived.
BRIEF DESCRIPTION OF THE DRAWINGS
The detailed description particularly refers to the accompanying
figures in which:
FIG. 1 is a cross sectional view through one embodiment of the
modular hip prosthesis of the present invention installed in a
femur;
FIG. 2 is a view similar to FIG. 1 showing another embodiment of
the present invention;
FIG. 2a is a partial view of a modification of the collar component
and nut arrangement of the embodiment shown in FIG. 2;
FIG. 3 is an exploded perspective view of another embodiment of the
present invention showing a modified stem member and body
member;
FIG. 4 is a view similar to FIG. 3 showing another embodiment of
the present invention with a collar component and an interlocking
key and keyway in the body member and stem member;
FIG. 5 is a perspective view of another embodiment of the present
invention showing a modified body member;
FIG. 6 is a perspective view of another embodiment of the present
invention showing a modified stem member;
FIG. 7 is an exploded perspective view of another embodiment of the
present invention showing a modified stem member and a modified
neck and body member;
FIG. 7a is a perspective view of an adapter block for use when the
collar component shown in FIG. 7 is not utilized;
FIG. 7b is a view similar to FIG. 7A showing a modified adapter
block;
FIG. 7c is a perspective view of a modification of the neck member
shown in FIG. 7; and
FIG. 8 is a cross sectional view through the assembly illustrated
in FIG. 7 installed in the femur.
DETAILED DESCRIPTION OF THE DRAWINGS
Referring now to FIG. 1, FIG. 1 shows a modular hip prosthesis 10
of the present invention inserted into a femur 12 in which the head
and neck portions (not shown) have been resected. The resection of
the head and neck portions of the femur 12 has been performed to
leave a generally planar surface 14 on the femur 12. A cavity 16
has been formed in the femur 12 to receive the prosthesis 10. It
will be understood that the resection procedure and the procedure
for forming the cavity are well known in the art. It will also be
understood that the cavity 16 may be formed to be the exact same
size as the prosthesis 10, or if necessary, the cavity 16 may be
formed to be somewhat larger than the size of the prosthesis 10.
The cavity 16 shown in FIG. 1 is illustrative of the latter, with
the cavity 16 being somewhat larger than the size of the prosthesis
10.
The prosthesis 10 includes an elongated stem member 20 that is
generally circular in cross section and includes a lower portion 22
and an upper portion 24. The upper portion 24 has a diameter
slightly less than the diameter of the lower portion 22. The
demarcation between the upper portion 24 and the lower 22 is marked
by a chamfer 26. The upper extremity of the stem member 20
terminates in a threaded end 28. The lower portion 22 may have any
of several surface treatments, including, but not limited to,
blasted, smooth, porous bony-ingrowth, and coated.
A body member 30 is shown disposed over the upper portion 24 of the
stem member 20, with the upper portion 24 extending through a bore
32 in the body member 30. The body member 30 includes an upwardly
and inwardly (medially) facing surface 34 in which a threaded bore
36 has been formed. The surface 34 defines a plane 35 that is
generally coincident with a plane defined by the base of the neck
(not shown) that has been resected from the femur. The body member
30 may be formed by casting or machining and may have any of the
several outer finishes discussed in connection with lower portion
22 of the stem member 20. It will be appreciated that, in the
orthopedic implant art, having parts which can be made using
machining techniques rather than casting techniques provides
significant advantages.
A neck member 40 which replaces the natural neck of the femur (not
shown) extends generally upwardly and inwardly from the surface 34.
The neck member 40 includes a threaded projection 42 that engages
the threaded bore 36 in the body member 30. A head member 44 is
formed on the proximal end of the neck member 40, with the head
member 44 replacing the natural head of the femur (not shown).
Notches 46 are formed in the surface of the neck member to permit a
wrench (not shown) to be used to tighten the neck member 40 into
the body member 30.
The prosthesis 10 is assembled by first inserting the upper portion
24 of the stem member 20 through the bore 32 in the body member 30.
A nut 50 is then engaged with the threaded end 28 of the stem
member 20 to secure the stem member 20 to the body member 30. It
will be understood that the distal end of the bore 32 in the body
member 30 includes a chamfer to mate with the chamfer 26 on the
stem member 20 to provide a secure engagement. The neck member 40
is then installed in the body member 30 by engaging the threaded
projection 42 with the threaded bore 36. The neck member 40 is then
tightened using a wrench (not shown) in the notches 46.
To install the assembled prosthesis 10 in the femur 12, a grouting
material 52, or bone cement material, is first injected into the
cavity 16. The prosthesis 10 is then placed in the cavity 16 such
that the distal end of the body member 30 rests upon the surface
14, and the lower portion 22 of a stem member 20 extends downwardly
into the cavity 16. The grouting material 52 surrounds the lower
portion 22 of the stem 20 and in some cases a portion of the body
member 30 and acts in a known manner to secure the prosthesis 10
within the femur 12.
FIG. 2 shows another embodiment of the present invention that is
configured to fulfill slightly different anatomical requirements
that may be indicated during the replacement procedure. This
embodiment is configured to replace a portion of the femur 12 in
which only the head and neck portions (not shown) have been
resected. The Calcar portion 54 of the femur 12 has been left
intact. Therefore, a smaller body member 55 is shown that can be
disposed totally within the cavity 16 in the femur 12. Also, a
collar 56 is provided that mates with the body member 55 and
extends over the Calcar portion 54 of the femur 12. The collar 56
is provided to distribute the load between the body member 55 and
the Calcar portion 54. In this embodiment, the body member 55
includes a key 58 that is received in a keyway 60 that is formed in
the stem 20. The key 58 and keyway 60 cooperate to prevent any
rotation of the body member 55 with respect to the stem member 20.
The prosthesis 10 shown in FIG. 2 is inserted into the cavity 16 of
the femur 12 that has been filled with a grouting material 52 to
secure the prosthesis 10 in a known manner.
FIG. 2a shows a modification of the embodiment shown in FIG. 2.
Specifically, the collar 56 of FIG. 2 is replaced by a collar 62
that extends over the threaded end 28 of the stem member 20. A
chamfered hole 66 is formed in the extension of the collar 62 that
receives the threaded end 28 of the stem member 20. A nut 64 with a
chamfer 68 is provided to engage the threaded end 28 of the stem
member 20 with the chamfer 68 of the nut engaging the chamfered
hole 66 of the collar 62. The chamfer 68, 66 cooperate to securely
engage the collar 62 between the body member 55 and the nut 64.
FIG. 3 shows another embodiment of the present invention including
a slightly modified stem member 70 that engages the body member 55
of the embodiment shown in FIG. 2. Specifically, the stem member 70
includes a shorter upper portion 71 in comparison to the stem
member 20. A chamfer 72 is provided between the upper portion 71
and the main portion of the stem member 70. The body member 55
includes a modified bore 74 extending therethrough to receive the
stem member 70. The modified bore 74 has a chamfer 73 to mate with
the chamfer 72 on the stem member 70. This modified stem member 70
and body member 55 may be used when additional strength in the stem
member 70 is required, such as, for example, when the stem member
70 has a diameter smaller than normal. FIG. 3 also shows an
extension 76 (shown only in dotted) that may be added to the body
member 55 to make the body member 55 similar to the body member 30
shown in FIG. 1. The extension 76 will be required if the Calcar
portion 54 (FIG. 2) of the femur 12 is being resected and
replaced.
FIG. 4 shows another embodiment of the present invention similar to
the embodiment shown in FIGS. 2 and 2a. In the embodiment shown in
FIG. 4, the key 58 on the body portion 55 and the keyway 60 on the
stem member 20 are located on the opposite side compared to the
embodiment shown in FIG. 2. Also, the collar 78 is similar to the
collar 62 shown in FIG. 2a, however the hole 80 in the extension
does not contain a chamfer, thereby permitting the use of the
unchamfered nut 50 to engage the threaded end 28 of the stem member
20.
FIG. 5 shows another embodiment of the present invention in which a
body member 82 is formed in a somewhat irregular shape. The
irregular shaped body 82 may be preferable for insertion into
certain femurs (not shown). It will be understood that the body
member 82 may be a cast material, or may be machined in a known
manner and may have a surface treatment similar to that described
in relation to the body member 30 (FIG. 1).
FIG. 6 shows another embodiment of the present invention having a
modified stem member 84. Specifically, the stem member 84 includes
a curved lower portion 85 that may be inserted into the cavity 16
in the femur 12 (not shown) when the anatomical indications so
dictate. It will be understood that the stem member 84 may be mated
with either the body member 30, the body member 55, or the body
member 82, as discussed previously.
FIG. 7 shows yet another embodiment of the present invention. In
this embodiment, a stem member 86 is provided that includes a lower
portion 88 that is coated with a bone-ingrowth porous metal
coating. Bone-ingrowth coatings are known in the art, and it will
be understood that this type of stem 86 is adapted to be inserted
into a bone without the use of any grouting or cement material. The
upper end of the stem 86 includes a groove 90 that is adapted to
mate With a stem clip 94 after the stem member 86 has been inserted
through a bore 93 in the body member 92. It will be understood that
the groove 90 and the stem clip 94 function in a manner similar to
the threaded end 28 and nuts 50, 64 shown in FIGS. 1-3 to secure
the stem member 86 within the body member 92. The body member 92
includes a generally upwardly and inwardly (medially) facing
surface 96 that is formed to include a generally trapezoid-shaped
slot 98. A collar 100 is provided that includes a generally
trapezoidal-shaped projection 110 that is configured to dovetail
into the slot 98 to align and position the collar 100 in the body
member 92. The collar 100 includes a hole 112 formed therethrough
that aligns with a threaded hole 114 in the body member 92 when the
collar 100 is mated with the body member 92.
FIG. 7 also shows a modified neck member 118 that includes a
threaded end 120 and a tapered end 122. The neck member 118 is
secured to the body member 92 by passing the threaded end 120
through the hole 112 in the collar 100 and into the threaded hole
114. A separate head member 124 is shown that is formed to include
a tapered hole (not shown) that mates with the tapered end 122 of
the neck member 118 to secure the head member 124 to the neck
member 118. It will be understood that the neck member 118 and the
head member 124 can be of various shapes and sizes other than those
illustrated in FIG. 7. A collar clip 126 is shown that inserts
under the projection 110 of the collar 100 to lock the neck member
118 in position after it has been screwed into the threaded hole
114 in the body member 92.
FIG. 7a shows an adapter block 130 that may be inserted into the
slot 98 if the collar 100 (FIG. 7) is not used. The adapter block
130 is sized to fill the slot 98 so that the surface 96 on the body
member 92 will be generally planar. The adapter block 130 shown in
FIG. 7a is configured to accept the stem clip 126 as described
above.
FIG. 7b shows another adapter block 132 that also may be inserted
into the slot 98 if the collar 100 (FIG. 7) is not used. The
adapter block 132 is sized to fill the slot 98 so that the surface
96 on the body member 92 will be generally planar. The adapter
block 132 differs from the adapter block 130 in that block 132 is
used when no stem clip 126 will be utilized.
FIG. 7c shows a modified neck member 140 that is similar to the
neck member 118 shown in FIG. 7. Neck member 140 differs in that
the threaded end 120 (FIG. 7) is replaced by a tapered end 142 that
may be inserted into a tapered hole (not shown) in any of the body
members, such as body member 92 (FIG. 7).
FIG. 8 shows the prosthesis of FIG. 7 assembled and in a use
position. To assemble the embodiment shown in FIG. 7, the stem
member 86 is first inserted through the bore 93 in the body member
92. The stem clip 94 is then engaged with the groove 90 to secure
the stem member 86 within the body member 92. The collar 100 is
then engaged with the body member 92 by sliding the projection 110
into the slot 98 so that the hole 112 aligns with the threaded hole
114. The neck member 118 is then threadingly engaged into the
threaded hole 114 by the threaded end 120. After the neck member
118 is tightened, the collar clip 126 is inserted under the
projection 110 to lock the neck member 118 in position. The head
member 124 is then inserted over the tapered end 122 of the neck
member 118 to secure the head member 124 to the neck member
118.
The assembled prosthesis is then inserted into the cavity 16 of the
femur 12 so that the collar 100 extends over the Calcar portion 54.
It will be understood that in this embodiment the cavity 16 is
excavated only to the extent necessary to permit the assembled
prosthesis to exactly fit within the cavity 16. As discussed
previously, the lower portion 88 of the stem member 86 will be
secured within the femur 12 by the natural growth process of the
bone into the porous surface. Illustratively, the body member 92
may also be coated with a bone-ingrowth material to enhance this
ingrowth process.
Although specific embodiments have been shown assembled in FIGS.
1-8, it will be understood that the components shown in the figures
may be interchangeable, and a prosthesis may be assembled utilizing
combinations of the illustrated components. This ability to select
different sizes and shapes of components to assemble a prosthesis
greatly enhances the flexibility available at the time of the
operation. Thus, depending upon the anatomical indications
presented by the patient, numerous combinations are available to
assemble a prosthesis at the time of the operation to meet the
exact requirements for that patient.
Although the invention has been described in detail with reference
to preferred embodiments and specific examples, variations and
modifications exist within the scope and spirit of the invention as
described and defined in the following claims.
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